An osteochondral lesion (osteochondritis dissecans or OCD) is an injury or small fracture of the cartilage surface of the talus which typically occurs via a crush or injury to the surface of the bone during the abnormal motion of the ankle in a sprain. The OCD sits on the medial or lateral shoulder of the talar dome and is situated on the top and the side of the joint surface. The talus bone is part of the collection of bones which forms the lower part of the ankle joint.
With an inversion or eversion stress on the ankle, the talus and tibia and/or fibula will contact each other with massive stress, resulting in a compression or shear stress on the surface of the talus and underlying injury.
In an ankle allograft replacement, an entirely new joint surface (made of bone and cartilage harvested from a fresh cadaver) is typically implanted instead of replacing the ankle joint with a replacement made of metal and plastic. The operation involves removal of a segment of bone and cartilage from the recipient ankle and identical bone cuts made on the ankle cadaver graft.
A cutting jig is typically used to harvest the ankle joint from the cadaver ankle. The block is fixed on to the cadaver (e.g., using one or more K-wires) and the cuts are made to remove the ankle joint which is then implanted into the recipient. Properly fitting a donor bone section into the resection site for a patient is important for recovery time, longevity, and performance for the patient.
However, such cutting jigs are time-consuming to set up and use and may not enable enough of a precise cut for providing a bone graft suitable for resection and implantation. Such an ill-fitting graft may subsequently increase the time for bone in-growth and patient recovery time. Moreover, part of the imprecise cuts may occur because of improper offsetting of the jigs in failing to account for kerf losses incurred when cutting into the bone due to the saw or blade.
Accordingly, there exists a need for methods and apparatus which facilitate procedures such as calcaneal osteotomy procedures by providing for easier and more accurate blade positioning and adjustment features and which provide for shorter procedure times.